Illustration of the water stars ( Callitriche ), 1 = Callitriche hamulata , 2 = Callitriche hermaphroditica
The water stars are annual to perennial herbaceous plants that creep on the ground or partially or completely under the water surface . The stem grows thread-like and is covered with opposite, stipule-less leaves . The shape and arrangement of the leaves vary greatly depending on the location. Plants below the surface of the water often have lanceolate or linear leaves and long internodes . Plants whose stem grows above the water have shorter internodes so that the elliptical or spatulate leaves are in rosettes. Terrestrial plants usually have ovate or almost circular leaves. In the axils of the stem there are glandular scales, both stem and leaves are covered with scale-shaped trichomes .
The water star species are single- sexed ( monoecious ) or dioecious ( dioecious ). The unisexual flowers are in the armpits and occur either singly or in pairs with a male and a female flower. There is no flower cover, two bracts are crescent-shaped or missing. The male flowers mostly consist of a single, rarely up to three stamens / stamens with a slender stamen and a kidney-shaped anthers . In the female flowers are two carpels to a top permanent ovary grown, which is divided by a false septum into four chambers. There is a single anatropic ovule in each ovary chamber . The two free styluses are thread-shaped.
Systematics and distribution
The genus Callitriche was established by Carl von Linné . The generic name Callitriche is derived from the Greek words kallos for physical beauty and thrix and trichos for hair (because of the growth habit).
The position of the genus Callitriche within the Bedecktsamer was long unclear because of a lack of characteristics, especially because of the strongly reduced flowers. Some of them were in a monogeneric family Callitrichaceae. According to the knowledge of molecular biology, they are classified in the plantain family (Plantaginaceae).
The following water star species have been identified in Germany:
- Pedunculate water star ( Callitriche brutia Petagna , Syn .: Callitriche pedunculata DC. ): It occurs in southern and western Europe, east to Italy, north to southern Sweden.
- Blunt-edged water star ( Callitriche cophocarpa Sendtner , Syn .: Callitriche polymorpha Lönnr. )
- Hook water star ( Callitriche hamulata Kütz. Ex WDJKoch , Syn .: Callitriche intermedia Hoffm. ): It is widespread in Europe.
- Autumn water star ( Callitriche hermaphroditica L. , Syn .: Callitriche autumnalis L. , Callitriche virens Goldb. ): It occurs in Europe mainly in Northern and Eastern Europe.
- Nutty water star ( Callitriche obtusangula Le Gall )
- Swamp water star ( Callitriche palustris L. , Syn .: Callitriche verna L. , Callitriche vernalis W.DJKoch )
- Flat-fruited water star ( Callitriche platycarpa Kütz. ): It occurs in Europe and Turkey, mainly in north-western and central Europe.
- Pond water star ( Callitriche stagnalis Scop. ): It is native to Eurasia and North Africa and is a neophyte in North America, Australia and New Zealand.
- Truncated water star ( Callitriche truncata Guss .; Syn .: Callitriche hermaphroditica subsp. Truncata (Guss.) Jahand. & Maire ): It occurs in Europe mainly in southern and western Europe; but its distribution area also includes North Africa and the Middle East. One can distinguish three subspecies.
Other species in Europe and the Mediterranean are:
- Callitriche cribrosa Schotsman : It occurs in Morocco, Algeria, Spain, Portugal and Italy.
- Callitriche lenisulca Clavaud : It occurs in southern Europe and the Middle East.
- Callitriche lusitanica Schotsman , which is found in Portugal, Spain, Morocco, Algeria and Tunisia.
- Callitriche pulchra Schotsman , which occurs on the southernmost Greek island, on Gavdos , on Cyprus and in Libya .
- Callitriche regis-jubae Schotsman : It occurs in Morocco, Tunisia, Spain, Portugal and Sardinia .
To this end, the following species were introduced from North America and have been naturalized in France:
Other types are:
- Callitriche deflexa A. Braun ex Hegelm. : It occurs in South America.
- Callitriche fallax Petrov : This endemic occurs only in Kamchatka .
- Callitriche lechleri (Hegelm.) Fassett : It occurs in Argentina, Chile and Uruguay.
- Description in the Western Australian Flora . (engl.)
- Henriette Dorothea Schotsman: Callitriche L. In: TG Tutin, VH Heywood, NA Burges, DM Moore, DH Valentine, SM Walters, DA Webb (eds.): Flora Europaea . Volume 3: Diapensiaceae to Myoporaceae . Cambridge University Press, Cambridge 1972, ISBN 0-521-08489-X , pp. 123–126 (English, limited preview in Google Book Search).
- Inga Hedberg, Olov Hedberg: Callitrichaceae. In: HJ Beentje: Flora of Tropical East Africa. Balkema, Lisse 2003, preview .
- Matthias Breitfeld: Help for collecting and determining species of the genus Callitriche (water stars). In: Communications on floristic mapping in Saxony-Anhalt. Volume 6, 2001, pp. 35-41 (PDF file) ( Memento from March 16, 2014 in the Internet Archive ).
- Henriette Dorothea Schotsman: Callitriche L. In: Thomas Gaskell Tutin et al .: Flora Europaea. Volume 3, Cambridge University Press 1972. Pages 123-126.
- Callitriche in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland. Retrieved December 4, 2018.
- Callitriche at Floraweb.
- Pertti Johannes Uotila, 2013: Plantaginaceae. Datasheet Callitriche In: Euro + Med Plantbase - the information resource for Euro-Mediterranean plant diversity.